The technical field of wireless power transmission technologies includes a method using radio frequency (RF) and a method using a magnetic field. Among these, examples of the method using a magnetic field include a magnetic field induction-based contactless power transmission method, a magnetic field beam shaping-based short-distance power transmission method, and a magnetic field resonance-based short-distance power transmission method.
Technologies using a contactless method have been gradually used with portable electronic devices, portable terminals, rechargeable pads, and so on, in accordance with current trends. In the future, technologies are expected to be applied to more portable devices, but there is a problem in that a power transmission distance is very short. In addition, magnetic field resonance-based wireless power transmission technologies are designed in such a way that a transmitter and a receiver resonate with each other to significantly enhance transmission efficiency but are disadvantageous in that transmission efficiency is rapidly reduced as a distance between a transmitter and a receiver is increased.
The method using RF is based on a technology that is currently and significantly widely used in forms such as radio frequency identification (RFID) and requires a physiological approach in the future because a problem in terms of very low maximum power transmission rating is not overcome and maleficence is not proved in a clinical test and a verification test. Since the magnetic field beam shaping-based short-distance power transmission method uses ferrite, the method can be applied to an electric vehicle, an electric rail car, or the like due to a large size and weight, but it is disadvantageous that the method cannot be easily applied to a portable small-sized electronic device.
Accordingly, there is a need for a wireless charging system that has enhanced efficiency and directivity and is harmless to humans.
The above information is presented as background information only to assist with an understanding of the present disclosure. No determination has been made, and no assertion is made, as to whether any of the above might be applicable as prior art with regard to the present disclosure.